Got off the shot.. no period yet, spotted after -- could i be preg?

Well i was on the shot for 6 months. I had went and got that gardocil shot and completely forgot to get my birth control shot, so for two months i was not on the shot(and i was bleedin a lot and didnt know why!) well then i went and got back on it.. and it made me gain weight instantly so after that i never went back to get on it again. i was going to wait for my periods to get back to normal again cuz it was just makin me bleed and spot a lot. well its been two months now since ive been off the shot.. and still have not had a period!! a few weeks ago i had unprotected with a guy, and a few days later spotted a light light pink and it was only on the toilet paper twice! Now my hurt, and i get dizzy and nausious a lot. ?